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Illuminating DRL and Turn Lights with Single Common Lamp

Illuminating DRL and Turn Lights with Single Common Lamp

The article discusses a simple circuit for enabling the turn signal lamp of any car to carry out a two-way function of DRL lights as well as well the stipulated turn lights. The idea was requested by Mr. Artem.

Technical Specifications

Thank you for your fanaticism with electronics, this is really noticeable through your blog. I've been experimenting with some of your circuits, and everything is okay for now.

Here I kindly ask your professional advise on my project.

Some tiny vehicles have a certain lack of room to place LED lights in order to look fine. For one of those, Nissan Micra i was asked to combine LED Turns and DRL lights without placing one next to another..

Considering a small city car ergonomics i searched the market.

I ordered twin color Y+W 1Watt 350mA LED-Emitters from China, so I could combine both functions by means of some kind a controller at one spot.

And as it often happens, seller did not provide any specs for his product.

4-pin LEDs actually have common "+" so i can not drive six of them in series or implement any known driver. Please advise something useful, I believe you are able to.

Thanks in advance,


DRL and Turn Lights with Single Common Lamp


The Design

The proposed circuit which combines and enables illuminating DRL and turn signal lamps through a single common lamp can be seen above.

The circuit basically allows the same lamp (preferably LEDs) to implement a dual function of DRL lights as well as turn signals, depending on which one is switched ON.

The DRL switch is supposed to be switched ON permanently, so that the connected lamp illuminates through the TIP122 transistor, and as soon as the turn signal flasher is switched ON, the TIP122 is instantly disabled through the BC547, allowing the turn signal to flash the LED at the given frequency.

The above happens since the BC547 becomes triggered ON through the turn signal switching and keeps the TIP122 base grounded and disabled.

The 100uF/25 plays a crucial role here, and makes sure that the BC547 stays disabled for both the ON and the OFF periods of the turn signal inputs, therefore this capacitor might require some tweaking until the right minimum timing is determined.

Bigger values will work but this might result in a delayed switch ON of the DRL each time the turn signal is deactivated, therefore the 100uF value could need some adjustments.

The 10k preset at the base of the TIP122 may be used for determining the brightness level on the DRL, so this becomes an added feature in the design.

Feedback from Mr. Artem

Thank you for the circuit.

But it seems  you get me a little wrong. I wanted the circuit to drive 350ma double color leds, which has single common "+"positive and two "-"negative pins for white and yellow respectively. Both lamps are in single body for ergonomic reasons.

Your suggested circuit doing the job well but we must take two colors with common positive pin in account.

Solving the Circuit Query

As per the above response, the earlier diagram can be modified as shown below for executing the new function.

I have assumed the LEDs to be having the current limiting feature originally, therefore it's not been shown here or included in the proposed designs. Otherwise 5 ohm, 2 watt resistors could be included in series with the respective negative lines of the LED module.


About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!

10 thoughts on “Illuminating DRL and Turn Lights with Single Common Lamp”

  1. I have a circuit design request… It’s an automotive application, 12VDC, negative ground.

    Using a single, momentary, N.O. pushbutton I’d like to accomplish the following functionality to a 12v relay.

    Action 1 – Tap the pushbutton and the relay would pulse/fire quickly 3 times… end of cycle/command
    Action 2 – Press and hold the pushbutton and the relay would latch on.
    Action 3 – If the circuit is in “Action 2”, a momentary press on the button would reset the relay, readying the circuit for a #1 or #2 action again.

    This is a “flash to pass” or “High Beams ON” function, depending upon the duration of the button press.

    • Action 1 and 2 may be possible but 3 will not be possible using a normal circuit (without microprocessor), resetting will require a separate switch.

  2. hi iam having problems with the last circuit with the dual drl with dimming drl when indicator is turned on please help thanks in advance

  3. hi. can you suggest a circuit diagram for dusk to dawn control. i have manages to replicate the ones that are used in automatic night lamps which illuminate a couple of led's. Do you have any schematics which can drive regular incandescent bulbs, without using a relay.

    You response will be highly appreciated.

    I have had a sweep through your blog. Your hard work and inputs are admirable..
    Hats off to you. Keep the good work going.

    Linus Fernandes
    9004805177 / 8698303609 / 9321279202

    • Hello Mayank, you can use it but the unused 3 opamps will need to be appropriately terminated for preventing long term affects to the ICs

  4. Hello sir ,
    I want to make a 12V 90 Amp battery charger with full charge detector. I have a 500watt inverter transfarmer . Please help me


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